Proposal: user defined attributes

[Walter Bright]

On 3/17/2012 2:55 PM, Manu wrote:
> I tend to think of 'struct's as 'passive', and compile-time annotations would
> provide me with every use case I can imagine for my own purposes in the case of
> structs. classes seem far more likely to need stateful attributes.

I currently find the notion of runtime attribute state to be fraught with all 
kinds of unresolved and murky issues with no obvious answer:

1. construction/destruction
2. shared
3. const/immutable
4. thread locality
5. allocated statically or dynamically
6. shared library issues?

If the attribute is code, when does that code get run?

1. on initialization
2. on termination
3. on read
4. on write
5. what about read/write?